Dynamic Adaption of Resource Aware Distributed Applications

Dynamic adaptation has become an important issue when designing and developing distributed applications in order to manage their Quality of Service (QoS). This is especially challenging when distributed applications run in environments in which resources vary unpredictably over time. To deal with fluctuations in resource availability and inherent heterogeneity of distributed environments requires dynamic adaptation of each application. This trend motivates the design of resource-aware applications ensuring a given performance level by adapting their behavior to changing contexts. To tune the use of resources, adaptive systems include the necessary mechanisms to modify applications' behavior. This paper presents a general distributed middleware for enabling behavior adaptation of distributed applications. The middleware combines application designer specification of alternative execution behaviors with information about the execution environment context for deciding when and how to adapt itself according to the available resources. A description language specifies applications' behavior and the description of their related resource use. The QoS management requires a common execution model for all applications. Simulations of the QoS management of heterogeneous applications illustrate our proposal and show the benefits. In addition, we discuss lessons learned from our experience.